/*_############################################################################
  _##
  _##  SNMP4J 2 - TsmSecurityParameters.java
  _##
  _##  Copyright (C) 2003-2011  Frank Fock and Jochen Katz (SNMP4J.org)
  _##
  _##  Licensed under the Apache License, Version 2.0 (the "License");
  _##  you may not use this file except in compliance with the License.
  _##  You may obtain a copy of the License at
  _##
  _##      http://www.apache.org/licenses/LICENSE-2.0
  _##
  _##  Unless required by applicable law or agreed to in writing, software
  _##  distributed under the License is distributed on an "AS IS" BASIS,
  _##  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  _##  See the License for the specific language governing permissions and
  _##  limitations under the License.
  _##
  _##########################################################################*/

package org.snmp4j.security;

import org.snmp4j.asn1.BERInputStream;
import org.snmp4j.smi.OctetString;

import java.io.IOException;

/**
 * {@link SecurityParameters} implementation for the {@link TSM}
 * security model.
 * @author Frank Fock
 * @version 2.0
 * @since 2.0
 */
public class TsmSecurityParameters extends OctetString implements SecurityParameters {

    private int securityParametersPosition;
    private int decodedLength = -1;

    public TsmSecurityParameters() {
        super();
    }

    @Override
    public int getSecurityParametersPosition() {
        return securityParametersPosition;
    }

    @Override
    public void setSecurityParametersPosition(int pos) {
        this.securityParametersPosition = pos;
    }

    @Override
    public int getBERMaxLength(int securityLevel) {
        return getBERLength();
    }

    @Override
    public void decodeBER(BERInputStream inputStream) throws IOException {
        long startPos = inputStream.getPosition();
        super.decodeBER(inputStream);
        decodedLength = (int) (inputStream.getPosition() - startPos);
    }

    /**
     * Gets the position of the {@link org.snmp4j.ScopedPDU}.
     *
     * @return
     *    the start position in the {@link BERInputStream}.
     */
    public int getScopedPduPosition() {
        if (decodedLength >= 0) {
            return decodedLength + getSecurityParametersPosition();
        } else {
            return getSecurityParametersPosition() + getBERLength();
        }
    }

}
